US 12,403,454 B2
Methods of chromium catalyst activation to reduce gels and improve melt index potential
Max P. McDaniel, Bartlesville, OK (US); Zhihui Gu, Bellarie, TX (US); Ted H. Cymbaluk, Seabrook, TX (US); Anand Ramanathan, Bartlesville, OK (US); Julian Abrego, Houston, TX (US); Taryn L. Huber, Houston, TX (US); and David W. Dockter, Kingwood, TX (US)
Assigned to Chevron Phillips Chemical Company LP, The Woodlands, TX (US)
Filed by Chevron Phillips Chemical Company LP, The Woodlands, TX (US)
Filed on Apr. 30, 2024, as Appl. No. 18/650,230.
Claims priority of provisional application 63/499,507, filed on May 2, 2023.
Prior Publication US 2024/0367155 A1, Nov. 7, 2024
Int. Cl. B01J 23/26 (2006.01); B01J 21/08 (2006.01); B01J 37/08 (2006.01); B01J 37/14 (2006.01); C08F 10/02 (2006.01)
CPC B01J 23/26 (2013.01) [B01J 21/08 (2013.01); B01J 37/08 (2013.01); B01J 37/14 (2013.01); C08F 10/02 (2013.01); C08F 2500/07 (2013.01); C08F 2500/12 (2013.01)] 26 Claims
OG exemplary drawing
 
1. A process to produce an activated chromium catalyst, the process comprising:
(i) contacting a pre-catalyst with a first inert atmosphere at a temperature T1 in a range from 500° F. to 700° F. (260° C. to 371° C.), wherein the pre-catalyst comprises a silica support and:
from 0.1 to 5 wt. % chromium;
from 0.1 to 10 wt. % titanium; and
from 1 to 5 mol nitrogen/mol titanium;
(ii) subjecting the pre-catalyst to cycles of a first oxidizing atmosphere at a temperature T2 in a range from 500° F. to 700° F. (260° C. to 371° C.) and a second inert atmosphere at a temperature T3 in a range from 700° F. to 900° F. (371° C. to 482° C.),
wherein subjecting the pre-catalyst to the first oxidizing atmosphere causes an exothermic increase in temperature from T2 to T3, at which point the pre-catalyst is subjected to the second inert atmosphere which results in cooling the pre-catalyst from T3 to T2,
until (1) the exothermic increase in temperature in the first oxidizing atmosphere is less than or equal to 50° F. (28° C.) within 15 min, or (2) heat must be added to maintain T3 in the presence of the first oxidizing atmosphere;
(iii) heating the pre-catalyst in a third inert atmosphere to a temperature T4 in a range from 1000° F. to 1400° F. (538° C. to 760° C.) and holding the pre-catalyst at T4 in the third inert atmosphere for a hold time t1 in a range from 1 hr to 15 hr;
(iv) cooling the pre-catalyst in a fourth inert atmosphere to a temperature T5 in a range from 900° F. to 1200° F. (482° C. to 649°° C.), wherein T5 is less than T4;
(v) subjecting the pre-catalyst to a second oxidizing atmosphere at T5 for a hold time t2 in a range from 30 min to 10 hr;
(vi) cooling in a third oxidizing atmosphere to a temperature T6 in a range from 500° F. to 700° F. (260° C. to 371° C.) to produce the activated chromium catalyst; and
(vii) purging the activated chromium catalyst in a fifth inert atmosphere at T6 and cooling to ambient temperature.